Ma J X, Gillaspie D T, Plummer E W, Shen J
Condensed Matter Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Phys Rev Lett. 2005 Dec 2;95(23):237210. doi: 10.1103/PhysRevLett.95.237210. Epub 2005 Dec 1.
The magnetic and transport behaviors of manganites are critically related to the spatial distribution and correlation of doped holes. Using in situ scanning tunneling microscopy, we have imaged both occupied and unoccupied states simultaneously in a hole-doped (La(5/8-0.3)Pr0.3)Ca(3/8)MnO3 epitaxial thin film grown by laser molecular beam epitaxy. Doped holes localized on Mn4+ ion sites were directly observed with atomic resolution in the paramagnetic state at room temperature. In contrast to a random distribution, these doped holes show strong short-range correlation and clear preference of forming nanoscale CE-type charge-order-like clusters. The results provide direct visualization of the nature of intriguing electronic inhomogeneity in transition metal oxides.
锰氧化物的磁性和输运行为与掺杂空穴的空间分布及相关性密切相关。利用原位扫描隧道显微镜，我们在通过激光分子束外延生长的空穴掺杂（La(5/8 - 0.3)Pr0.3）Ca(3/8)MnO3外延薄膜中同时成像了占据态和未占据态。在室温下的顺磁态中，以原子分辨率直接观察到了位于Mn4+离子位点上的掺杂空穴。与随机分布不同，这些掺杂空穴表现出强烈的短程相关性以及形成纳米级CE型电荷有序类团簇的明显偏好。这些结果提供了对过渡金属氧化物中有趣的电子不均匀性本质的直接可视化。
